- 作者: Yi-Tzang Tsai; Chen-I Lin; Hung-Kai Chen; Kuo-Ming Lee; Chia-Yi Hsu; Shun-Jen Yang; Ning-Hsing Yeh
- 作者服務機構: School of Life Science, Institute of Microbiology andImmunology, National Yang-Ming University, Taiwan
- 中文摘要: --
- 英文摘要: The short arms of five human acrocentricchromosomes contain ribosomal gene (rDNA) clusterswhere numerous mini-nucleoli arise at the exit of mitosis.These small nucleoli tend to coalesce into one or a fewlarge nucleoli during interphase by unknown mechanisms.Here, we demonstrate that the N- and C-terminal domainsof a nucleolar protein, hNopp140, bound respectively toa-satellite arrays and rDNA clusters of acrocentric chromosomesfor nucleolar formation. The central acidicand-basic repeated domain of hNopp140, possessing aweak self-self interacting ability, was indispensable forhNopp140 to build up a nucleolar round-shaped structure.The N- or the C-terminally truncated hNopp140 causednucleolar segregation and was able to alter locations of therDNA transcription, as mediated by detaching the rDNArepeats from the acrocentric a-satellite arrays. Interestingly,an hNopp140 mutant, made by joining the N- andC-terminal domains but excluding the entire central repeatedregion, induced nucleolar disruption and globalchromatin condensation. Furthermore, RNAi knockdown ofhNopp140 resulted in dispersion of the rDNA and acrocentrica-satellite sequences away from nucleolus that wasaccompanied by rDNA transcriptional silence. Our findingsindicate that hNopp140, a scaffold protein, is involved inthe nucleolar assembly, fusion, and maintenance.
- 中文關鍵字: --
- 英文關鍵字: Acrocentric chromosomes; Alpha-satellite; DNA; Centromere; Nopp140; Nucleolus; rDNA